In a booklet published at the time of the meeting, Audi’s head of Innovations Lighting / Lighting Electronics Stephan Berlitz depicts some of his ideas for exterior lighting concepts. The lighting mastermind appears fascinated by a number of OLED properties such as their extremely thinness. OLED lamps for automotive use can be built in a sandwich manner: Two glass plates with a flat polished surface enclose the active assembly and make it watertight. This object is just over a millimeter thick. If a low voltage is applied, photons are emitted in the electric field, and the surface is illuminated. The thinner the layer, the greater the brightness. In order to obtain different colors, various polymers can be used. Multiple OLEDs can be placed one behind the other for mixed color effects. White light can be generated by adding the basic colors.
Berlitz’ team has built an OLED rear light for the Q7 model. Four small red OLED plates aligned next to one another generate the desired light. Eight flat segments make up the curved yellow strip for the flashing turn indicator.
According to Berlitz, such a homogeneous visual effect would not be possible with standard LEDs. “Such LEDs are individual points of light that need additional optical devices – reflectors, optical conductors or scatter optics. OLED surfaces are themselves the source of light, and the thin plates also look attractive. They light up extremely fast, develop only a small amount of heat and don’t consume any more energy than conventional light-emitting diodes. OLEDs suit Audi perfectly because they combine high-end technology, maximum precision and super design,” Berlitz said. He also pointed out that OLEDs have reached a lifetime of several tens of thousands of operating hours – quite close to the requirements of the automotive industry.
Nevertheless, the Audi roadmap for introducing OLEDs to series production will take several years to put into effect. At the current level of development, the new diodes only withstand low currents and the acceptable temperature range ends at about 80 degrees Celsius. OLEDs will make an appearance as rear lights in the relatively near future; for brake lights, which have to be about five times brighter, a few more years will elapse. But, according to the booklet, the company can also imagine white OLEDs being used for daytime running lights and side lights.
The biggest target of all – especially for Audi’s designers – are three-dimensional OLEDs. The first prototypes are now appearing as part of a project with public support. Audi designers are fascinated – OLEDs allow them to create delicate, almost weightless ring-shaped sources of light, installed on various levels in the rear light units of an Audi TT.
Free forms can perhaps be obtained by means of an intermediate solution – arranging the small plates three-dimensionally. Clusters of this kind could be located anywhere on the body, as seen on a model of the future Audi R8 OLED concept. It has strips consisting of hundreds of triangular OLEDs on its sides, back and inside the car. This will permit the car to be identified in a whole series of ways that can be constantly varied.